encrypt using chacha

src/chacha_io.rs

@@ -0,0 +1,45 @@
+use c2_chacha::stream_cipher::{NewStreamCipher, SyncStreamCipher, SyncStreamCipherSeek};
+use c2_chacha::{ChaCha12, ChaCha20};
+use std::convert::TryInto;
+use std::io::{Read, Result, Write};
+
+pub struct ChaChaReader<'a>(ChaCha20, &'a mut Read);
+
+impl<'a> ChaChaReader<'a> {
+    pub fn new(key: &[u8], nonce: &[u8], source: &'a mut Read) -> ChaChaReader<'a> {
+        ChaChaReader(ChaCha20::new_var(key, nonce).unwrap(), source)
+    }
+}
+
+impl<'a> Read for ChaChaReader<'a> {
+    fn read(&mut self, buf: &mut [u8]) -> Result<usize> {
+        let red = self.1.read(buf)?;
+        self.0.apply_keystream(buf);
+        Ok(red)
+    }
+}
+
+pub struct ChaChaWriter<'a>(ChaCha20, &'a mut Write);
+
+impl<'a> ChaChaWriter<'a> {
+    pub fn new(key: &[u8], nonce: &[u8], sink: &'a mut Write) -> ChaChaWriter<'a> {
+        ChaChaWriter(ChaCha20::new_var(key, nonce).unwrap(), sink)
+    }
+}
+
+impl<'a> Write for ChaChaWriter<'a> {
+    fn write(&mut self, buf: &[u8]) -> Result<usize> {
+        let mut cipher_text = [0u8; 256];
+        let mut written = 0usize;
+        for chunk in buf.chunks(cipher_text.len()) {
+            cipher_text[0..chunk.len()].copy_from_slice(&chunk);
+            self.0.apply_keystream(&mut cipher_text[0..chunk.len()]);
+            written += self.1.write(&cipher_text[0..chunk.len()])?;
+        }
+        Ok(written)
+    }
+
+    fn flush(&mut self) -> Result<()> {
+        self.1.flush()
+    }
+}